Stewart Logan, LEO III at Ravenscraig
Colvilles Ltd., Ravenscraig Steelworks
A Short Description of the Leo3/32 Production Planning & Control System
Introduction
Colvilles Ltd. Steelmakers installed a Leo 3 (No.32) in their Ravenscraig Works
in Motherwell in 1963. In 2021, Dr. William (Bill) Jack, leader of the systems
development team described in a paper to the Leo Computers Society the systems
developed and run on this computer. I was the lead analyst on the Production
Planning and Control system and was asked by the Society if I could provide
further detail on how Lector OMR techniques were used. I was not involved in
the concurrent development of the payroll system so my recollections are only of
the PPC system. This request was made nearly 60 years after we had acquired the
Leo and all documentation had long since been destroyed. We clearly did not
have the foresight to realise that what we were developing could be regarded as
pioneering.
Locating some lost information
Perhaps a word is in order as to how I managed to get a little more detail. In 1967
I had just got married and was working on draft drawings of a house I planned to
build. By pure chance, I recently found that one of these drawings had, on the
back of it, most of a flow chart of the Production Planning & Control system that
we had implemented. I think it is probably just missing 1 or 2 operations down
one edge so it gives a very good picture of the scope of the system. It is
unfortunately very faded and not really suitable for adding to the Leo archives. I
was able to pick up much detail of the use of Lector documents from it but,
regretfully, have not managed to trace any of the actual documents. This flowchart, however, enabled me to extract further information about the system.
Why optical mark reading?
The primary requirement of the system was to provide information as at 6am for
day staff who started work at 8.30am and for production meetings at 9am. This
was not possible to achieve using conventional data preparation.
Collection of order details
Lector documents were used to collect data on new orders, order amendments,
order cancellations and order completions. These documents were completed by
sales personnel in an office environment. This information was input to the
system run at 6am daily thus providing an updated order file.
Collection of steel movements and change of status
As Dr. Jack explained in his paper, for process scheduling reasons, it was not
possible, unless an order was very small, to move all of the material for it through
the plant together. However, by tracking the movement of every piece of material,
whether or not allocated to an order, the system could provide the requirements
of every order and the present progress towards order completion including
whether there was a shortfall of material for it.
Lector documents collected information on the creation of steel slabs, their
dimensions and allocation to orders and the coil of steel produced from each slab.
Thereafter, Lector documents were used to record every movement and change
of status of a coil. In later processing, a coil could be cut along its length into 2
or more narrower ones. Coils could also be cut into bundles of sheets and further
processed. Lector documents were also used to track material through these
processes. Where a coil was despatched to Gartcosh Works finishing processes
the tracking continued until despatch from there as either coils or bundles of
sheets. The data recorded on each coil or bundle as it passed through the processes
included a code for the process, any change to dimensions, any change to weight
and any change to grade (which resulted in it being removed from its allocated
order). A lector document was also used to collect information on surplus stock
being allocated to suitable orders. The tracking of coil and sheet bundles
movement thus covered all processes until the material was despatched.
The Lector documents were completed by recorders on the shop floor (see
appendix 1). The data was collected through a 24 hour period and input to the
Lector machines at Ravenscraig and Gartcosh. Trials showed that time was
probably insufficient to get the Gartcosh Lector paper-tape output driven over to
Ravenscraig after 6am. add it to the Ravenscraig data, complete the system run
and get the Gartcosh print-outs delivered all before 8.30am. A paper-tape reader
to paper-tape punch link was thus commissioned between Gartcosh and
Ravenscraig.
The system produced production reports for morning progress and planning
meetings at 9am. Additionally, order file reports were produced showing the
present status of each order so that remedial action could be taken if it was
running late or short of material. Lists were produced of the stock ahead of each
production unit to assist schedulers with their work and to greatly simplify
periodic stock checks. Subsequent stock-checks showed the system to be highly
accurate.
Analysis of the recovered flow chart indicates that there were 52 Cleo routines
providing vetting and files updating together with about 50 printed reports. There
were upwards of 30 sort routines. I do not have actual figures but there must have
been many hundreds of order and stock changes every 24 hours.
Development team
Initially, the team comprised about 9 personnel who worked on systems analysis
and the early stages of systems design. As work progressed, 6 of the team then
programmed the analytical work. It seems remarkable that the system design and
implementation was done by only about 3 systems analysts and 6 analystprogrammers using Cleo, which speaks highly of that language. The basic
tracking and reporting system was implemented in late 1965 by the team that had
only been trained early that year. However, continuous enhancements followed
in the use of all the data that was being collected.
Further development
Round about 1970, under a British Steel reorganisation, the Leo 3 was to be
replaced by an IBM 360/40. It indicates how highly the Leo system was regarded
that the suite of programs was rewritten almost unchanged in PL1 to run on the
IBM machine. This rewritten system which was implemented in 1973 still used
Lector documents for several years until replaced by on-line terminals.
Stewart Logan
November 2021
Appendix 1 – Design of Lector forms
Trial OMR documents were printed and tested out on shop-floor production
recorders. Most of the data to be collected was numeric; items such as material
identity, any changes to dimensions, weight, grade or anything else that could
change at any specific production unit. Alpha data was very limited and normally
restricted to one of several characters. The test documents had the particular
processing unit identity pre-printed on them. As most of the date to be collected
was numeric, each character of a particular parameter to be input was represented
by four, what we called, soup-bowls labelled 1, 2, 3 and 6. Thus, by filling in no
more than 2 of these soup-bowls by pencil, any digit from 0 to 9 could be
represented. Thus recording a material identity of 5 numeric characters would be
represented on the pre-printed form by 5 groups of these 4 soup-bowls. The
choices of the limited acceptable alpha characters were all represented by
individual soup-bowls. We were advised that shop-floor personnel would not
understand this. We argued that anyone who knew how to fill in a pools coupon
would soon master it. Trials showed that we were right. Subsequently, once the
system was implemented, we only had one failure – a person who was dyslexic.
